Authors: B. Fouconnier, A. Román-Guerrero, J. Vernon-Carter
Affilation: Universidad Veracruzana, Mexico
Pages: 626 - 629
Keywords: silica nanoparticles, CTAB, hexadecane-in-water emulsions, interfacial rheology, DSC, emulsion stability
The synergistic interactions between silica (SiO2) nanoparticles and a surfactant cetyltrimethylammonium bromide (CTAB) on the shear viscoelastic properties of the hexadecane-water (H/W) interfacial films as well as the formation and stability of emulsions were investigated. For that purpose, different amounts of colloidal silica dispersions and CTAB in decreasing ratios (R1, R2 and R3) were used to tune the hydrophobicity of the nanoparticles. Interfacial creep compliance-time studies of the CTAB–SiO2 films at the Hexadecane–water interface were carried out in order to understand the mechanisms of the CTAB–SiO2 aggregates adsorption and their interactions at the interface. The characterization and stability of the emulsions was determined by DSC and optical microscopy. The emulsions displayed polydisperse droplet size and the average droplet size of the emulsions decreased as the CTAB–SiO2 ratio diminished. DSC aging tests indicated that only emulsions made with R3 presented changes in the average droplet size probably due to slower reorganization of the clusters at the droplet interface until a well structured film was developed. Despite that E-R1 and E-R2 presented a relatively large non spherical droplets they were highly stable against coalescence due to the formation of a solid-like interfacial layer.